分类: 生物学 >> 生态学 提交时间: 2024-01-12 合作期刊: 《干旱区科学》
摘要: Studying the spatiotemporal variations in ecosystem services and their interrelationships on the Loess Plateau against the background of the gully control and land consolidation (GCLC) project has significant implications for ecological protection and quality development of the Yellow River Basin. Therefore, in this study, we took Yan'an City, Shaanxi Province of China, as the study area, selected four typical ecosystem services, including soil conservation service, water yield service, carbon storage service, and habitat quality service, and quantitatively evaluated the spatiotemporal variation characteristics and trade-offs and synergies of ecosystem services from 2010 to 2018 using the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model. We also analysed the relationship between the GCLC project and regional ecosystem service changes in various regions (including 1 city, 2 districts, and 10 counties) of Yan'an City and proposed a coordinated development strategy between the GCLC project and the ecological environment. The results showed that, from 2010 to 2018, soil conservation service decreased by 7.76%, while the other three ecosystem services changed relatively little, with water yield service increasing by 0.56% and carbon storage service and habitat quality service decreasing by 0.16% and 0.14%, respectively. The ecological environment of Yan'an City developed in a balanced way between 2010 and 2018, and the four ecosystem services showed synergistic relationships, among which the synergistic relationships between soil conservation service and water yield service and between carbon storage service and habitat quality service were significant. The GCLC project had a negative impact on the ecosystem services of Yan'an City, and the impact on carbon storage service was more significant. This study provides a theoretical basis for the scientific evaluation of the ecological benefits of the GCLC project and the realization of a win-win situation between food security and ecological security.
分类: 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间: 2016-05-12
摘要: Pin1 is the only known cis-trans isomerase that recognizes pThr/pSer-Pro in proteins, relevant to the pathogenesis of Alzheimer' s disease (AD). Pin1 regulates the structures and functions of some molecules that are related to AD, inhibits the main AD pathological characteristics such as neurofibrillary tangles (NFTs), senile plaques (SPs), and cerebral amyloid angiopathy (CAA), promotes the differentiation of neural progenitor cells (NPCs) to neurons, and to some extent prevents the occurrence and development of AD. Meanwhile, Pin1 dysfunction in vivo may be involved in the pathogenesis of AD. Nevertheless, whether Pin1 could be a therapeutic target for the prevention and treatment of AD still needs to be verified clinically. Considering of the poor efficacy of AD medicines that target each single molecule in brain, the "combined multiple-target medicine" focusing on Pin1 and other related molecules may be a therapeutic strategy for AD in the future.
分类: 生物学 >> 生物物理学 提交时间: 2016-05-11
摘要: Developing chimeric lysins with a wide lytic spectrum would be important for treating some infections caused by multiple pathogenic bacteria. In the present work, a novel chimeric lysin (Ply187N-V12C) was constructed by fusing the catalytic domain (Ply187N) of the bacteriophage lysin Ply187 with the cell binding domain (146-314aa, V12C) of the lysin PlyV12. The results showed that the chimeric lysin Ply187N-V12C had not only lytic activity similar to Ply187N against staphylococcal strains but also extended its lytic activity to streptococci and enterococci, such as Streptococcusdysgalactiae, Streptococcus agalactiae, Streptococcus pyogenes, Enterococcus faecium and Enterococcus faecalis, which Ply187N could not lyse. Our work demonstrated that generating novel chimeric lysins with an extended lytic spectrum was feasible through fusing a catalytic domain with a cell-binding domain from lysins with lytic spectra across multiple genera.
分类: 生物学 >> 生物物理学 >> 肿瘤学 提交时间: 2016-05-15
摘要: Tumor necrosis factor receptor-associated protein 1 (TRAP1) is abnormally expressed in many cancers. In this study, we showed that TRAP1 is aberrantly upregulated in breast tumors compared to control tissues. TRAP1 knockdown downregulates mitochondrial aerobic respiratory, sensitizes cells to lethal stimuli, and inhibited tumor growth in MDA-MB-231 and MCF-7 breast cancer cells in vivo. TRAP1 overexpression, however, enhances the capacity to cope with stress conditions. These evidences suggested that TRAP1 is required for tumorigenesis. We also found that TRAP1 regulates the mitochondrial morphology. Relatively lower TRAP1 levels are associated with the rod-shaped mitochondrial phenotype in invasive and metastatic MDA-MB-231 breast cancer cells; on the contrary, higher TRAP1 levels are associated with the tubular network-shaped mitochondrial phenotype in non-invasive MCF-7 cells. Interestingly, the expression of TRAP1 in human breast cancer specimens inversely correlates with tumor grade. Overexpression of TRAP1 in MDA-MB-231 cells causes mitochondrial fusion, triggers mitochondria to form tubular networks, and suppresses cell migration and invasion in vitro and in vivo. These data link TRAP1-regulated mitochondrial dynamics and function with tumorigenesis of breast cancer and suggested that TRAP1 may therefore be a potential target for breast cancer drug development.
分类: 生物学 >> 生物物理学 >> 生物力学与生物流变学 提交时间: 2016-05-15
摘要: B lymphocytes use B cell receptors (BCRs) to sense the physical features of the antigens. However, the sensitivity and threshold for the activation of BCRs resulting from the stimulation by mechanical forces are unknown. Here, we addressed this question using a double-stranded DNA-based tension gauge tether system serving as a predefined mechanical force gauge ranging from 12 to 56 pN. We observed that IgM-BCR activation is dependent on mechanical forces and exhibits a multi-threshold effect. In contrast, the activation of isotype-switched IgG- or IgE-BCR only requires a low threshold of less than 12 pN, providing an explanation for their rapid activation in response to antigen stimulation. Mechanistically, we found that the cytoplasmic tail of the IgG-BCR heavy chain is both required and sufficient to account for the low mechanical force threshold. These results defined the mechanical force sensitivity and threshold that are required to activate different isotyped BCRs.
分类: 生物学 >> 生物物理学 >> 肿瘤学 提交时间: 2016-05-11
摘要: Malignant pleural effusion (MPE) is a common complication caused by malignant diseases. However, subjectivity, poor sensitivity, and substantial false-negative rates of cytology assay hamper accurate MPE diagnosis. The aim of this study was to assess whether CD163+CD14+ tumor-associated macrophages (TAMs) could be used as a biomarker for enabling sensitive and specific MPE diagnosis. Pleural effusion samples and peripheral blood samples were collected from 50 MPE patients and 50 non-malignant pleural effusion (NMPE) patients, respectively. Flow cytometry was performed to analyze cell phenotypes, and RT-qPCR was used to detect cytokine expression in these monocytes and macrophages. A blinded validation study (n = 40) was subsequently performed to confirm the significance of CD163+CD14+ TAMs in MPE diagnosis. Student's t test, rank sum test, and receiver operating characteristic curve analysis were used for statistical analysis. Notably, CD163+CD14+ cell frequency in MPE was remarkably higher than that in NMPE (P < 0.001). In a blinded validation study, a sensitivity of 78.9 % and a specificity of 100 % were obtained with CD163+CD14+ TAMs as a MPE biomarker. In total (n = 140), by using a cutoff level of 3.65 %, CD163+CD14+ cells had a sensitivity of 81.2 % and a specificity of 100 % for MPE diagnosis. Notably, MPE diagnosis by estimating CD163+CD14+ cells in pleural effusion could be obtained one week earlier than that obtained by cytological examination. CD163+CD14+ macrophages could be potentially used as an immune diagnostic marker for MPE and has better assay sensitivity than that of cytological analysis.
分类: 生物学 >> 生物物理学 提交时间: 2016-05-05
摘要: A novel cleavable amphiphilic peptide (CAP) was designed to be specifically responsive to fibroblast activation protein- (FAP-), a protease specifically expressed on the surface of cancer-associated fibroblasts. The CAP self-assembled into fiber-like nanostructures in solution, while the presence of hydrophobic chemotherapeutic drugs readily transformed the assemblies into drug-loaded spherical nanoparticles. The disassembly of these nanoparticles (CAP-NPs) upon FAP- cleavage resulted in rapid and efficient release of the encapsulated drugs specifically at tumor sites. This Transformers-like drug delivery strategy could allow them to disrupt the stromal barrier and enhance local drug accumulation. Therapeutic results suggested that drug-loaded CAP-NPs hold promising tumor specificity and therapeutic efficacy for various solid tumor models, confirming its potential utility and versatility in antitumor therapy.
提交时间: 2017-05-02
摘要: Poly[butylene terephthalate]-poly[tetramethylene glycol] [PBT-PTMG] copolymer is prepared with terephthalic acid [PTA] rather than its dimethyl ester [DMT] as starting material by a two-step melt polycondensation. This process includes the synthesis of PB
分类: 物理学 >> 核物理学 分类: 物理学 >> 地球物理学、天文学和天体物理学 提交时间: 2023-09-12
摘要: The neutron capture cross sections (${n, upgamma}$) of Bromine was performed with the time-of-flight (TOF) technique at the Back-n facility of the China Spallation Neutron Source (CSNS). Prompt $ upgamma$-rays originating from neutron-induced capture events were detected by four C${}_6$D${}_6$ detectors. The pulse height weighting technique (PHWT) and the double-bunch unfolding method based on the Bayesian theory were used in the data analysis. To obtain reliable measurement results, background deductions, normalization, and corrections were carefully considered. The multilevel R-matrix Bayesian code SAMMY was used to extract the resonance parameters in the resolved resonance region (RRR). The average cross sections in unresolved resonance region the was obtained from 10 to 400 keV. The experimental results were compared with the data of several evaluated libraries and previous experiments in the resolved and unresolved resonance region. The TALYS code was used to describe the average cross sections in the unresolved resonance region. Astrophysical Maxwell average cross sections (MACSs) of ${}^{79,81}$Br from $ kT $ = 5 to 100 keV was calculated over a sufficiently wide range of neutron energies. At a thermal energy of $kT=30$ keV, the MACS value for ${}^{79}$Br 638$ pm$64 mb is in good agreement with the KADoNiS recommended value. By contrast, the value of 293$ pm$29 mb for ${}^{81}$Br is substantially higher than those of the evaluated database and the KADoNiS recommended value.